Reversible ribbon feeding mechanism for typewriting machines



Nov. 4, 1952 R. D. DODGE REVERSIBLE RIBBON FEEDING MECHANISM FOR TYPEWRITING MACHINES 4 Sheets-Sheet 1 Filed June 21, 1947 w 0 M0 N0 0 m M R ATTO RNE Nov. 4. 1952 R. D. DODGE REVERSIBLE RIBBON FEEDING MECHANISM FOR TYPEWRITING MACHINES 4 Sheets-Sheet 2 Filed June 21, 1947 lNVENTOR RONALD D. DODGE 2? ATTORN Y Nov. 4, 1952 R. D. DODGE REVERSIBLE RIBBON FEEDING MECHANISM FOR TYPEWRITING MACHINES 4 Sheets-Sheet 3 Filed June 21, 1947 INVENTOR RONALD 0. BY

, ATTOR EY NOV. 4, 1952 DODGE 2,616,547

REVERSIBLE RIBBON FEEDING MECHANISM FOR TYPEWRITING MACHINES Filed June 21, 1947 4 Sheets-Sheet 4 INVENTOR RONALD D. 00065 ATTO R N EY Patented Nov. 4, 1952 REVERSIBLE RIBBON FEEDING MECHANISM FOR. TYPEWRITING MACHINES Ronald D. Dodge, Poughkeepsie, N. Y., assignor to International Business vMachines Corporation, New York, N. Y., a corporation of New York Application June 21, 1947, Serial No. 756,174

2 Claims. (Cl. 197 162) This invention relates to typewriting machines.

The principal object of the present invention is to provide an improved ribbon mechanism.

Anobject is to provide a ribbon mechanism which is operated by a source of power other than. thetype bars or the type bar operating trains.-

An object is to provide a ribbon mechanism which is suitable for use in power operated typewriters.

An object is to provide .a ribbon mechanism whichis more positive and reliable in its action.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. lis a verticle section of a power operated typewriter and shows the ribbon vibrator mechanisrn.

Fig. 2 is a vertical elevation showing the power meansfor actuatingthe ribbon mechanism and theribbon feeding mechanism associated with the left hand ribbon spool.

Fig.3 is va detail view showing the ribbon feeding mechanism of Fig. Zin reversed condition.

Fig. 4 is a large scale view of the ribbon vibrator mechanism appearing in Fig. 1 and shows the mechanism in position to effect printing through the lower zone of the ribbon.

Fig. 5 1s aplan view of the mechanism shown inFig. 4'.

Fig. dis a view showing the ribbon vibrator mechanism adjusted to print through the middle zoneof the ribbon.

Fig.7 is a viewshowing the ribbon vibrator mechan smadiusted to print through the upper zoneof theribbon.

8 shows theribbon vibratormechanism in condition fortyping stencils- Fig. 9,is.a detailview of the reversingshaft.

Fig...10,is a planfviewof the means for pivotally supportingthe left ,hand ribbon spool.

In Fig.1 thereiis shown a vertical section of a power. operated typewriter. The character keys iil are pivoted;.0n .a cross rod H and guided at their front enri s by.a suitable key comb !2, the keysbeingrestored by springs is. The keys Iii controL power mechanism which. includes the power roller l4 normally rotatingin the direction of the arrow when the machine is in use. Eachkegqcontrols itsownpower unit, all of which coact with the power roller M to operate the corv fulcrum bar H longitudinally adjustably mounted in the support bar i8. The support bar 18 1s slotted at 58a to receive both the sub-levers i6- and the rounded ends of the associated fulcrum bars ii. The sub-levers iii are held in engagement with their fulcrum bars H by means of springs 19 which are anchored to suitable lugs formed in the fulcrum bars ll. Theupper end of each sub-lever i6 is connected by link 20 to an arm lea formed in the associated type bar l5.- Only one type bar l5 and one sub-lever IS with its associated parts are shown in Fig. 1 but it will be understood that there is a set of these parts for each character key it in the machine.

The type bars i5 are pivotally mounted by means of a curved pivot wire 25 (Fig. 1) in the usual segment 22 attached to and forming part of the usual type basket (not shown). This type basket may be case shiitable for the purpose of printing upper case characters or, if desired, the platen 23 may be shiftable for the same purpose. The segment 22 may be provided with the usual type guide 24 and the ribbon Vibrator 25 which isvertically guided on the type guide 2 and normally occupies the position of Fig. 1 in which it is below the printing line. The ribbon vibrator is actuated and controlled by novel means hereinafter. to be described.

Each power unit, besides the sub-lever it, includes an L-shaped cam 26 pivoted at [6b on the sub-lever i6 and urged in a counterclockwise direction by a spring 21 anchored to an ear formed in the cam 26 and an ear formed in the sublever [6. The sub-lever I6 is formed with an extension on which is pivotally slidably mounted at ltd an interposer 28 having the offset lug or shoe 28a engaging the cam 26 and a similar lug 28b engaging an extension ma formed in the key NJ. The interposer 28 is urged in a clockwise direction by a sprin 29 which is anchored to an ear formed in the interposer 28 and to a stop lug We formed in the extension [60, and the spring also holds the interposer 28 in its left hand position (Fig. 1) with the pivot id at the right hand end of the slot by means of izglgch said interposer is mounted on the pivot The depression of the key l0 rocks the interclockwise direction, thereby causing the serrated tread portion 26a of the cam to engage the power roller i4 and be gripped thereby. The power roller then rotates the cam 26 and, due to the eccentricity of the cam tread with respect to the pivot lob, the sub-lever IE will be rocked in a clockwise direction against the tension of spring l9 and thereby actuate the type bar to printing position. Near the end of the actuation of the cam 26 by the power roller, a nose portion 18f formed in the cam 26 engages an adjustable spring prong 30a formed in the spring comb 30 and is arrested.

As is common in typewriting machines the power unit does not propel the type bar the full distance to the printing point with the power unit coupled to the driver throughout the whole cycle, but the adjustment of the spring prong 30a is such that the nose piece lfic will strike said prong before the type bar reaches the printing point and the remainder of the stroke of the type bar will be effected by virtue of the inertia of the power unit and the type bar. The point at which this takes place is determined by adjusting the spring prong 30a up or down by means of an adjusting screw 3| which is individual to each spring prong 311a and there is a spring prong for each power unit. The spring prongs 30a are formed as part of a comb spring 30 secured to the support bar [8. This spring comb 30 also is slotted to space apart and guide the adjustable fulcrum bars l1.

When the nose piece I60 strikes the spring prong 30a the cam tread 26a will be disengaged from the power roller l4 by a motion of translation in which the nose piece 160 slides to the right (Fig. 1) over the spring prong 39a. As soon as the tread 26a is released from the power roller l4 the spring 21 snaps the cam 26 back to the position of Fig. 1 relative to the sub-lever 16.

During the actuation of the type bar I by the power unit, hereinafter collectively referred to as the power unit l6, the interposer 28 is carried in a clockwise direction. If the key i0 should be held depressed, the left hand end of the lug 28b on the interposer will engage the right side of the extension I01; and the parts will stay in this position as long as the key is held depressed, thereby preventing the power unit from repeating. A slight clearance is provided between the extension Ma and the lug 28b in the normal position of the parts so that, when the key If) is released, the spring 29 will snap the interposer 28 back to the position of Fig. 1, permitting another release of the power unit by depression of the key I 0.

Ordinarily in a typewriting machine the ribbon mechanism and the ribbon vibrator are actuated by universal bars which are either driven directly by the power units or are actuated by the keys or certain parts of the trains of connections from the type bars to the keys. In the present case the ribbon mechanism is actuated by a separate power unit which is merely rendered effective by the operation of the type bar power units l6 through a universal bar actuated by the power units.

Pivotally mounted on the framework of the machine (Figs. 1 and 2) is a cross-shaft 32 on which is pivotally mounted a universal bar 33 in the form of a vane. This universal 'bar is engaged by nose pieces 169 formed in the sublevers l6 whereby, each time a power unit I6 is operated, the universal bar 33 will be actuated in a counterclockwise direction (Figs. 1 and 2) against the tension of a restoring spring 33a. anchored to the universal bar 33. This movement of the universal bar 33 is utilized to trip a power unit generally designated 34 in Fig. 2.

This power unit 34 includes a suitable frame pivoted at 3501. (Fig. 2) to a fixed frame piece 35 suitably supported in the machine framework. An elliptical cam 34a is pivoted at 34b in the frame of the cam unit 34 and cam 34a is provided with two pins 340 located on diametrically opposite sides of the pivot 34b and normally one or the other of the pins is engaged by an arm 34d pivoted at 34c in the frame of the power unit 34. This arm 34d is urged in a clockwise direction by a torsion spring 34 partly coiled around the pivot 34c and hooked to lugs formed in the arm 34d and in the frame of the power unit 34, respectively.

Also pivoted at 34c (Fig. 2) is a trip lever 34g having an off-set lug 34h coacting with one of two lugs 342' formed in the cam 34a on diametrically opposite sides of the pivot 34b. The spring actuated lever 34d pressing on one of the pins 340,

tends to rock the cam 34a in a clockwise direction, thereby holding the lug 341' in engagement with the lug 34h and in this position of the parts there is a small clearance between the tread of the cam 34a and an enlarged portion l4a formed in or suitably secured to the power roller 14.

The universal bar 33 is connected by a link 36 (Fig. 2) to the trip lever 34g whereby a counterclockwise motion imparted to the universal bar 33 by the power units l 6 will actuate the trip lever 349 in a clockwise direction and disengage the lug 34h from the lug 342'. At the same time a lug 34 formed in the trip lever 34g is positioned in the path of movement of the second lug 341'. The shaft 32 is provided at its ends with the arms 3211, one of which is connected by a link 31 to a lug formed in the frame of the power unit 34. When the elliptical cam 34a is released in the manner just described, its tread is brought into engagement with the portion I4a of the power roller l 4 which thereupon rotates the cam 34a in a clockwise direction (Fig. 2). Due to the eccentricity of the lobes of the cam 34a, a clockwise rocking motion is imparted to the frame of the power unit 34, thereby drawing the link 31 upwardly and rocking the shaft 32 in a counterclockwise direction.

The power unit 34 is restored by a spring 35b (Fig. 2) anchored to the frame of the power unit and to a lug carried by frame 35. This restoring movement is limited by a resilient bumper 350 on which the frame of the cam unit rests and which is carried by frame 35.

Attached to each of the arms 32a is a link 38, one for each ribbon spool, and these lin s actuate two separate ribbon feeding mechanisms, each associated with a ribbon spool. The drawings show the ribbon feeding mechanism located on the left hand side of the machine but it will be understood that the two mechanisms are similar in construction and. a description of one will sufiice for both. The side plates 39 of the main framework are formed with a large open cut-out portion 39a (Fig. l) to accommodate the ribbon spools of which the left hand spool is designated 40 in Figs. 2 and 3. The ribbon feeding and reversing mechanism for each spool is mounted as a unit in the cut-out 39a of the associated side frame 39 by means of a plate 4| attached by means of screws 42 to the plate 39.

Riveted to the plate 4| (Figs. 2, 3, and 10) is a shouldered stud lla which serves as one pivot acre-seer for the; rib n pool 4.0,,theot-b r pirot 'coneis ina of. a stud; 42a. formedin; the. end ofla: finger button;

42 carried by lear spring 413-, fixedly mounted. by means of the clamping screws 44 too. bracket extension 4|b, formed inthe. plate: 4| Bygrasping thebutton 42 (Fig. 10,) and pulling it to. the; right, the ribbon spool maybe readily, inserted in or removed fromthe machine.

The link 38 for the: left hand spool. 4|) is:c.on nected. to onearmg of a lever 45 (Figs. 2 and 3). pivoted on a stud 46 carried by the plate-.4|. One arm of; the lever 45 has pivoted, at. 45a 9. feed pawl. 41 which is urged'in a; clockwise. directionby a. prin 8- 'Ihef ed pawl 41.. isformedifromsheet:

metal and has an off-set lug;4.1c;enga ng theu u l rat het teeth 4.0a: formed in the; flanges of the. ribbon spool. 46, when. the. feed mechanism is;

in condition; to feed. tharibbon. on; the. left; hand.

spool as indicated in-Eia. 2;.

It is apparent? that each time a type. bar. [5 is operated by a power unit. 5, the: universal baralso. will, be operated and will. cause the power: unit 34 to be rendered operative intheimannerdee scribed above to impart an. oscillation. to: theshaft 32., thus thrusting both links 38 upwardly and to the left. If the pawl 41 in Fig; 2 is in engagement with the teeth 40a, the aforesaid movementv of the links 38 will cause the lever associated with the-pawl 41 to be actuated in a clockwise." direction, thereby'feeding the ribbon spool 45 in a clockwise direction. It: will be understood that. the lovers 45 for both feeding mechanisms will be oscillated each time a. power unit I5 is active to operate a type bar l5 but whether or not a ribbon spool is. actuated by its associated pawl 41 will-depend uponwhether or not the pawl is permitted; to engage the: ratchet teeth 4811.:

Means. are provided. for causing the pawls 41 to engage the teeth; 40a ofthe ribbon spools in alternation so as to cause one. ribbon spool to feed untilthe other is, exhausted and then render the other spool. effective to feed and. this mechanism is controlled by the tensionjproducedin the ribbon when the free running spool is exhausted. Pivoted at 49 on the plate 4.| is a lever50'to which is pivoted at 5|a a plate 5| shaped. somewhat: like a letter'G reversed righttol'eft. Pivoted at 5|b on. the plate 5|. is an interposer 52- which is connectedby a spring'link'53i to one arm of a tension lever 54 pivoted at MototheplateM. The tension lever 54 is" formed witha ribbon guide lug 54a having anopenribbon guiding slotv 54?) (Fig. 10) formed therein andisurgediin a'.clock-. wise direction against: a stop lug. 4|d by a spring 55.

The left handspool 40 is shown inLfree running condition in Fig. 3, that is, withthe ribbon R unwinding from. the spool and pawl 41' retracted. Due to the fact that the ribbon. is secured'to the spool, there will come a time when the ribbon will beno longer capable ofunwinding' from the spool 45 and this will anchor the ribbon. and, due to-the tendency of. the. ribbonto straighten, will rock the tension control lever 54 in a counterclockwisedirection (Fig. 3);. Due to thelink con' nection 53 interposer.- 54 willberocked clockwise into the path of an off-set lug- 45b formed in the lever 45. Consequently" thenext. oscillation of the lever 45 will cause. the; plate 5| to; be. shifted upwardly from the position of; Fig. 3. The plate 5| is formed with a long off-set lug- 5|c;.like the.

cross-barof' a- G, disposed between. the pawl. 41

and the teeth ite-s0: that; in the positionshown; in Fig: B thepaW-I 41 is. preventedfromz engaging;

i is being reversed.

6*. said; teethbllt when. the plate 5| is shifted upa wardlmasgjust describedto, theposition of Fig. 2,.

the pawl 41 will be permitted to. en age the teeth 46%, This renders pawl 41 effective to drive theribbon spool 48 with. each clockwise oscillation of the lever 45 as in Fig. 2 which illustrates the. left hand spool. feeding mechanism in .a driving condition.

In order to prevent retrograde. movement of the. spoolwhich is, being driven by; the operative pawl 41 there is provided a pawl 56 constructed somewhat similarly to the pawl 41 and similarly engaged by the. lug 5|c. The pawl 56 is urged in a. counterclockwise direction by a spring 51 ans chored to a lug formedin the plate 5] and alug formed in. the pawl. The pawl 56 ispivotallymounted. on a fixed dog 58 secured. tov the plate 4| by means of a screw 59, the dog 51 being prevented. from, turning on the plate 4| by a lug formed on the dog which extends into a hole formed in. the plate 4|.

The. plate 5| for the, left hand spool 40 has a loose pinconnection 68a (Figs. 2, 3,. and 9). with an arm. carried by a cross-shaft 6| journaled in the framework. The plate 5| for the right hand spool (not shown) is similarly connected at 620. to an arm 62 disposed on the opposite end of the shaft 5i adjacent the plate 4| for the right hand spool feeding mechanism so that the pins 65a, 62a for the respective ribbon spools are approximately apart on the shaft 6| (Fig. 9). It is apparent that, when the plate 5| is shifted upwardly from the position of Fig. 3 to the position of Fig. 2 in the manner described above, the

. plate 5| for the right hand ribbon spool will be drawn. downwardly and thereby disengage the pawls 41 and 55 for the right hand spool from the. ratchet teeth 40a thereon, thereby rendering that spool free running. This condition of the parts may be visualized in Figs. 2 and 3 by considering Fig. 3 as showing the mechanism for the right hand spool. It is apparent that the tension controlling lever 54 for the spool which is in free running condition renders such spool in driving condition whenever the spool becomes exhausted and tension is built. up by the ribbon sufiiciently' to cause the tension controlling lever 54 thereof to shift in a counterclockwise direction.

In order to enable the operator to change the directionof feed of the ribbon, the levers 55 are formed with. finger pieces 55a which may be grasped by the operator and pressed up or down, as desired.

In order to hold the plates 5| in their alternate shifted positions the arm 62 is provided with an extensionfiZb (Figs. 2, 3, and 9) engaged by one. branch of a toggle spring 63', the other branch being pivoted on a fixed stud 54 carried by the framework. The toggle spring 63 is fairly stiff with the result that the actuating" lever 45 and the interposer 52 of either spool 49 need only raise the associated plate M a little beyond the dead center position of the toggle'spring: 53 which thereafter becomes effective to snap the plate 5! to the. alternate position.

One of'the advantages of the ribbon mechanism described above is it imposes a very small but constant load on the type bar operating mechanism, particularly at the times when the ribbon In ordinary ribbon mechanisms the full power necessary to effect the reversal of the. ribbon feedin mechanism imposes an additional load on the type bar mechanism,.. causing the type bar to print lighter while the ribbon is reversing than at other times, and

thisis particularly true in power operated typewriters in which the force of the blow is beyond the control of the operator insofar as actuation of the keys is concerned. This is due to the fact that the power units for operating the type bars are adjusted to give an even impression of the type characters when one of the ribbon spools is running free as is normally the case, except during the brief periods when the ribbon is reversing. The result is that the additional load imposed on the type bar operating mechanism at the time of reversal imposes a considerable additional load thereon and slows up the operation of the type bars sufliciently to cause them to print light. If the ribbon mechanism is very sluggish in reversing as is very common in practice, it might happen that several characters may print lighter than others.

Since the power unit 34 operates invariably with a fixed but relatively large amount of power and this power is applied directly to the ribbon mechanism, the ribbon reverses immediately and the additional load is placed on the power roller M which has considerable surplus power for the purpose and is not applied to any particular type bar operating train. The tread portion Ma of the power roller which actuates the cam unit 34 is somewhat larger in diameter than the main part of the power roller in order to cause the ribbon mechanism to be actuated at a somewhat faster rate than the type bar in order to insure that the ribbon will be fully fed before the next type bar reaches printing position, and also to insure that the ribbon will be reversed immediately so as to minimize striking characters in succession through the same spot on the ribbon.

The ribbon vibrator 25 (Fig. 1) is actuated by mechanism shown in the lower left hand corner thereof and illustrated in successive manually set positions in Figs. 4 to 8. Mounted on the main framework near the middle of the machine is a frame 65 which extends vertically and has an offset lug 65a on which is pivoted the lever 66. the free end of which is connected by a link 61 to the ribbon vibrator 25. Pivoted to the lever 65 is a link 68 which, with a similar link 69, forms a toggle and the common pivot of the toggle link 68, 69 is connected by a shift link 70 to a shift lever H pivoted at 65b to the frame 65. The lower arm of the lever H is connected by a link E2 to the universal bar 33 near its midpoint. Since the universal bar 33 is actuated clockwise each time a character is printed, the link l2 will be thrust to the left in Figs. 4 to 8, thereby rocking the lever H clockwise and drawing the link 70 to the right. This tends to straighten the toggle 68, 69 and thereby rock the lever 66 counterclockwise to elevate the link 67 and the ribbon vibrator 25. The height to which the ribbon vibrator 25 is elevated depends upon the position of the pivot for the lower end of the toggle link 69. For this purpose the link 69 is pivoted at 13a to a control lever 13 secured to a shaft 14 journaled in the plate 65. The shaft 14 extends toward the left hand side plate 39 (Fig. and is provided with an arm 15 connected by a link 16 to a control key or tablet 'I'l. This tablet is suitably journaled for vertical rocking movement on the pivot 11a carried by a bracket 18 suitably fixedly mounted in the main framework. By flipping the tablet 11 up or down on the pivot 11a the link 16 may be moved selectively to right or left to control the movement of the ribbon vibrator. Normally the common pivot of toggle 68, 69 is coaxial with shaft 14 so that the ribbon vibration is not disturbed when tablet H is moved by hand.

Besides the normal retracted position of the ribbon vibrator 25 in which the ribbon R is located the ribbon, namely, a zone along the upper edge of the ribbon, a middle zone, and a zone along the lower edge, in order that the ribbon may be uniformly exhausted.

Fig. 4 illustrates the position of the mechanism whenthe ribbon vibrator is elevated to next-tominimumheight to effect striking of the type through the upper zone adjacent the upper edge of the ribbon. It is apparent that with constant angularity in movement of the lever Tl under the influence of the universal bar 33, the common pivot for the links 68, 69, i8 will move the lever 66 upwardly only a relatively small amount in Fig. 4, due to the fact that the lower pivot 78a occupies the lowest position but one of the four possible positions which it can take under control of the lever 13. If the lever 13 is now rocked counterclockwise a small amount the pin 73a will be raised to the position of Fig. 6 in which the angularity of the links 68, 69 has been increased. In this position the constant motion imparted to the common pivot for the toggle 68, 89 by the link l8 will cause the lever 66 to be elevated a greater distance than in Fig. 4 and the type will strike through the middle zone of the ribbon. When the lever 13 is rocked the maximum distance counterclockwise as in Fig. 7, the pin 13a is elevated still further and the ribbon vibrator will likewise be raised a further extent and cause the type to strike through the lower zone of the ribbon. When the lever 13 is set in the position of Fig. 8 the toggle 68, 69 is very nearly straight and the motion of the common pivot has very little effectin raising the lever 66 in fact, the lever 66 is first raised slightly and then pulled down slightly and this motion is insufi'icient to raise the ribbon vibrator far enough to elevate the ribbon to the printing line and is used when typing stencils. Hence, this position will be termed the stencil position.

The lever 70 is held in its various positions by means of a detent lever 19 which is pivoted at 650 in the frame and is urged in a clockwise direction by a spring 8! anchored to a lug formed in the lever 19 and to a lug formed in an extension arm 53b of the lever 13. The detent arm 19 is provided with a roller 19a which may engage either of two notches 13c, 13d to hold the lever 13 in the positions of Fig. 4 and Fig. 6, respectively. The lever 13 is provided with the bentover stop lugs 73:: and. 13f which not only limit the rotation of the lever '53 to approximately 45 but also yieldingly hold the lever in these limit- 7 ing pos ions, due to the'wedging of the roller 79a between the lugs and the edge of the lever I3. In order to' reduce noise due to the dropping of the ribbon vibrator 25, the frame 65 is formed with an extension arm 650 to which is attached aresilient bumper 65d which may be made of rubber or a resilient synthetic plastic of suitable characteristics.

While there have been shown and described and pointed out the fundamental novel features .of the invention, as applied to apreferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It isthe intention, therefore, to be limited only as indicated by the scope of the following claims:

What is claimed is:

1. A ribbon feeding mechanism for power operated typewriters and like machines having a main power actuator and power units for operating the type bars comprising a universal bar actuated each time one of said power units is operative, a ribbon feeding mechanism, and a power unit actuated by said main power actuator and rendered effective-by said universal bar for actuating said ribbon feeding mechanism.

2. In a typewriting machine, typing means including a series of type bars and an inking ribbon therefor, a series of character keys for controlling the typing means, a main power actuator, power units for operating the type bars and selectively engaged with ,the main power actuator by selec tive operation of said keys; mechanism for feeding said ribbon'including a pair of ribbon spools and a pair of oscillatable members, one for each ribbon spool, for feeding said spools, and including shiftable disabling means associated with each spool forflrendering the feeding mechanism operative and inoperative, said disabling means being interconnected whereby disabling the feeding mechanism with respect to either spool renders the feeding mechanism effective with respect to the other; means responsive to exhaustion of the ribbon from said spools; a pair of coupling devices, one for each spool and operated by the exhaustion responsive means for coupling the oscillatable members to the shiftable disabling means, said coupling devices being rendered effective to shift the disabling means to disable the feeding mechanism with respect to the spool which is full and render the feeding mechanism effective with respect to the spool which is exhausted; a power unit for actuating said feeding. mechanism and having a normally idle element operable by the power actuator to operate said oscillatable members in unison, and a universal bar actuated by any of said first named power units for rendering said last named power unit operable by the power actuator.

RONALD D. DODGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

